


Growing (Apart) Pains

by MaggicSorceress



Series: Maggic's Undertale Human AU [7]
Category: Undertale (Video Game)
Genre: Alternate Universe - College/University, Alternate Universe - Human, Alternate Universe - Modern Setting, But they know that, Gen, M/M, and sorting through them together, and they're working on it, their relationship is kinda unhealthy, two bros finally talking about their problems
Language: English
Status: Completed
Published: 2020-02-03
Updated: 2020-02-03
Packaged: 2021-02-28 04:22:51
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,899
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22537732
Author URL: https://archiveofourown.org/users/MaggicSorceress/pseuds/MaggicSorceress
Summary: Dream didn't like KillerBut he didn't have a reason for it.Not really.
Relationships: Dream/Cross (implied), Nightmare & Dream, Nightmare/Killer (implied)
Series: Maggic's Undertale Human AU [7]
Series URL: https://archiveofourown.org/series/1623928
Comments: 6
Kudos: 84





	Growing (Apart) Pains

Dream didn’t like his brother’s boyfriend.

Not one bit.

It was strange, because Dream normally liked most people and Killer wasn’t giving him any super bad vibes. He seemed to genuinely care about Nightmare but Dream just _didn’t like him._ He figured he would be happy, proud even, that Nightmare was settling into a steady relationship with someone. It was normal, it was good for him, but something about it all sat unpleasantly in Dream’s stomach. An odd mixture of anxiety and something else that he wasn’t quite sure what to call bubbling in his throat.

“I know that you said you were going out tonight…but there’s this movie that I thought we could watch together.” Dream was well aware that he was spewing nonsense at this point, but he _didn’t want Nightmare to go_. Said twin huffed at him from where he was trying to tame the wild locks of his dark hair. It was growing lighter at the roots; he’d have to dye it again soon.

“Dream, I’ve been home all week and _now_ you want to do stuff with me? I told you about this date weeks ago.” Nightmare bit at him. Normally, Dream wouldn’t have reacted to his tone, but this time he flinched. He didn’t want to stop his brother from having a good time, not at all. His twin was actually dressed nicely for once, in a pair of tight-fitting dark jeans and a deep purple sweater, and Dream was a little annoyed that Nightmare didn’t dress like that when _he_ asked him to, but was so willing when it was to impress Killer.

Now that was something. He shouldn’t feel _jealous_ of all things. Nightmare didn’t belong to him; he was as much his own person as Dream was. The thought of someone else taking that spot, that role of _protector_ and _care giver_ that had been Dream’s since their mom left made his chest clench painfully. That dark possessive part of his soul curling in on itself, as if it could feel ashamed.

“I know…I was just thinking.” Dream said, lame as far as excuses go.

“If you’re not gonna help me deal with my mess of hair, then why don’t you just go watch that movie you’re so excited about?” Nightmare said, sounding frustrated and a little anxious. To anyone else, what his twin had said would have made it seem like he was trying to get rid of the other, but Dream knew his brother’s language by now. His older brother wanted help, because he wanted to look good for this. And, apparently, Dream’s support _mattered_ to him. At least a little bit. The clenching feeling in Dream’s chest lessened as he crossed the room to his brother and snatched the comb from Nightmare’s hand.

“Sit down, I’ll help you.” Dream teased, smiling at Nightmare through the mirror. Nightmare dropped into the chair beside the desk and Dream began working away at some of the more stubborn knots in the other’s hair. “You know, you might have an easier time with all of this if you got a haircut.”

“Little late for that now, don’t you think?” Nightmare said, fiddling with a long strand of his bangs.

“Not really.” Dream said, parting his brother’s hair off to the side like he normally wore it. “I could cut it for you.”

Nightmare physically leaned away from him, looking back at Dream as if he had just pulled a knife on him. “No way in hell.”

“Why not?” Dream asked, slightly offended. “I cut my own hair all the time, why is yours different?”

“The last time you cut my hair I wound up with a bald patch on the side of my head!” Nightmare explained.

“I was five, Night!”

They held a bit of a staring contest for a minute or so before Nightmare relented, sagging back against the chair. “Fine, but if you make me look stupid and I have to cancel my date I’m shaving your head while you sleep tonight.” He said. Dream laughed, leaving the bedroom to grab a towel and his pair of hair scissors.

“That’s fair I guess.” Dream said, grabbing a can of spray-in conditioner as a side thought. When he returned, he threw the towel around his twin’s shoulders, making a mental note to vacuum later, and begun. They lapsed into comfortable silence, Nightmare scrolling through his phone as Dream sorted out his hair. After about half an hour, Dream poked his cheek and Nightmare looked up. His normally quite lengthy black hair was cut decently short against his neck, more noticeable, however, were how his long bangs had been cut and were swept off to the side, revealing both of his violet eyes. A bit startled by the sudden change in his appearance, he didn’t notice Dream was smiling at him until the other planted his chin on the top of his head.

“So?” Dream asked. “Do you like it?”

“You cut my bangs.” Nightmare said, more curious than accusing. Dream rolled his eyes.

“Yeah, because you look nicer when I can see your whole face. I think Killer would agree with me.” He said, wrapping his arms around Nightmare’s shoulders. “Speaking of, I think you should ditch those contacts of yours tonight.”

Nightmare tensed. “Why?”

“Because, Night.” Dream pleaded. “Your real eyes are so much prettier than those contacts you wear all the time. And I seriously doubt Killer is going to make fun of you for them.”

Nightmare frowned at him through the mirror. “Yeah but we’re going out for dinner. I’m not gonna be able to read the menu unless I bring my glasses.”

“Then bring your glasses.” Dream said. “You look cute in them anyway.”

“Dream…” Nightmare sighed, bordering on a whine. “He doesn’t even know this is my real eye colour, I can’t imagine him reacting to the fact that I have shitty eyesight.”

Dream hummed. “Yeah you might just kill him with cuteness.” Then, he winced as Nightmare flicked him harshly in the forehead. “Fine, fine I’ll stop. But I mean it. You look good.”

Nightmare eyed himself, like he wasn’t quite sure if he really believed everything that Dream was saying. Dream’s thoughts wandered a bit as his brother waged a mental war with himself. He thought about how much saying goodbye to this sort of thing would hurt. It was hard enough when Nightmare moved across town, at least he visited occasionally, but the thought that one day they would grow apart, and it would be _awkward_ to speak like this to each other made Dream want to cry. His brother must have noticed a change in his aura, because he was speaking suddenly.

“What’s bothering you?” Nightmare asked, staring at him through the mirror.

“Nothing. Just thinking.” Dream murmured, resisting the urge to bury his face into his brother’s hair to avoid the other’s eyes. Dream could never lie to him, not really, and it annoyed him immensely.

“Aren’t you always the one pestering me to talk to you about my feelings?” Nightmare said, raising an eyebrow. Dream almost chuckled.

“Don’t go using my words against me like that.” He said.

“Then tell me and I’ll stop bugging you.” Nightmare persisted. Dream sighed, squeezing Nightmare’s shoulders a little tighter. He wanted to tell him, because it really was bothering him, but it felt so _wrong_ to feel that kind of possessiveness.

“I just…” Dream started, trying to figure out how to put all the things he was feeling into words. “I don’t want you to go.”

It was simple that way. It summed everything up. Every bit of stress, every worry, every ounce of _sadness_ that Dream had been feeling lately, and he hoped desperately that his brother would catch the meaning behind his words without having to ask questions. He refused to meet the other’s eyes, focusing instead on trying to breathe past the lump in his throat.

“…I didn’t want you to either.” Nightmare said, and all of Dream’s previous worries about his twin understanding what he meant melted away. Only to be replaced by a new sort of feeling, one that bordered on guilt. “But…you had to.”

Finally meeting Nightmare’s eyes, he was surprised by the softness of the other’s gaze. He looked far away, like he was lost in his thoughts. “Why?” Dream asked, trying to answer his own thoughts more than wondering why Nightmare had never said anything to him.

“Because, moron.” Nightmare said, voice awfully quiet. “You’re important to me. And you were so…happy with him. Yeah, it’s hard and yeah it hurts but…that’s because we’ve never _had_ anyone else, Dream. It’s _always_ been just you and me.” Dream’s shoulders shook but he _wouldn’t cry_ , he wasn’t a baby anymore, _he wouldn’t._

“When I met Cross,” Nightmare began, “I was scared that he was going to hurt you. That he was going to worm his way into that massive heart of yours and break it, and when he didn’t, I wasn’t sure what to do. I felt like…like I was being replaced. Yeah, it’s a stupid thing to think but it was so strange to not be the first priority in your life anymore.” Dream finally gave in and buried his face into Nightmare’s hair. “I hated feeling like that, because you were so much happier all the time. Always smiling and laughing and I just…couldn’t bring myself to tell you how much this was eating me up inside. So, I get it, Dream. Now stop crying before you make me cry!”

Dream laughed wetly, chocking on a breath. “So-Sorry…” It was silent for a moment as Dream tried to calm his breathing. “Thanks…for telling me.”

Nightmare sagged against him. “Yeah, well, maybe we’ll have an easier time figuring this out if we do it together.”

Dream raised his head and wiped the tears from his cheeks, nodding as he fixed his brother’s hair again. “Yeah.” He agreed. “And Night?”

“Hm?”

“Cross is never gonna replace you, dummy. No one, no matter how important, could _ever_ replace you. Okay?” Dream said, soothing the other’s thoughts as well as his own. Nightmare’s jaw clenched and he looked away, nodding his head.

“Yeah, I know.” He said, voice thick. Dream hummed again, placing a quick kiss to the top of his twin’s head before he let him go.

“When’s Killer getting here?” Dream asked, changing the subject. Nightmare checked his phone before standing and slipping it into his back pocket.

“Five minutes, give or take.” Nightmare mumbled. “If he actually gets here on time.” Dream nodded, hesitated for a moment, and pulled his brother into a hug. Nightmare froze, only for a second, before he wrapped his arms around Dream’s back.

“Have fun tonight, okay?” Dream said through the tightness in his chest. “I love you.”

“…Love you too. And I will, I promise.”

On command, the doorbell rang, and they separated. Nightmare took a breath, worrying his lower lip. “…You sure I shouldn’t put in my contacts?”

Dream smiled at him. “Absolutely.”

And maybe, while Nightmare was rummaging around in his room for his glasses, when Dream answered the door, and saw Killer dressed the nicest he had seen him with a small black rose in his grasp, Dream genuinely smiled at him.

“Hey Killer! He’s on his way.”

**Author's Note:**

> My friend and I have been discussing a whole ass timeline for all of my Undertale fics because none of them outright contradict each other  
> This is the mess that came from one of those chats at 12 am XD  
> Hope you guys liked it! Comments and kudos are always appreciated!  
> -Maggic


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